The present invention is related to gas detection devices and in particular to a small, inexpensive dosage badge for determining the exposure of firefighters to toxic gases.
Fire atmospheres to which firefighters are exposed commonly include toxic gas components. For example, many fireman are injured as a result of contact with hydrochloric acid gases formed when polyvinyl resins are burned. Accordingly, it is desirable to be able to detect the presence of toxic gases and monitor the exposure dosage to the gas.
Gas detection apparatus are, in general, well known. Examples of prior art systems are described in the following U.S. Pat. Nos. 2,741,912 (Schultze), 3,067,015 (Lawdermilt), 3,084,658 (Schell), 3,112,998 (Grosskopf), 3,113,842 (Udall), 3,876,378 (Montagnon), 3,884,641 (Kraffczyk, and 3,933,029 (Rabenecker).
In general, the presently available apparatus for sampling fire atmospheres are either too cumbersome, too fragile, or too expensive for generalized field use. For example, the patent to Udall (U.S. Pat. No. 3,113,842) describes a gas detection apparatus comprising an evacuated gas chamber having a constricted portion containing a color sensitive indicator chemical that changes color upon exposure to a particular gas. The detection process is initiated by breaking the tip of the glass chamber. While small, the Udall device requires relatively complex fabrication techniques and is thus relatively expensive. Further, an open glass container is not ideally suited for a field environment. Accordingly, a small and lightweight but rugged and inexpensive, individually worn badge for indicating the exposure dosage to toxic gases is needed.
It is believed that the present invention provides such a small, inexpensive dosage indicator badge. A plurality of discs impregnated with a chemical indicator material, which respond with color changes upon predetermined dosage exposures to various toxic gases, are disposed on plastic substrate. A removable cover sheet, suitably formed of a pressure sensitive tape and including a nonadhesive pull-tab to facilitate removal is disposed on the face of the substrate to enclose the chemical detectors. Dosage monitoring is initiated by pulling the cover sheet off of the substrate to expose the impregnated discs.
The badge is easily fabricated and it is presently estimated that the badges can be constructed for less than $0.25 each. Three concentration badges in accordance with the present invention have been tested, weighing less than 0.02 ounces and only on the order of 1-2 inches by 3-4 inches by 0.02-0.05 inches in dimension. The badge can be mounted by adhesive or by a suitable clip on, for example, a hat or the sleeve of a firefighter. Further, the badge is small enough so that it can be disposed within the face mask of breathing apparatus to provide an indication of any leakage of toxic gases into the system.
It is the primary object of the present invention to provide a simple, inexpensive, reliable hazardous environmental condition indicator. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.